Methods and circuit arrangements for connecting an input circuit to a processor by means of a single-wire line are known, for example, in telecontrol systems. In these systems data is read from a remote transmitter via a single-wire line, which may be a telephone line, and a processor is fed with the signals obtained. The data of the transmitter is advantageously transmitted in digital form, which makes the transmission more reliable. If the transmitter includes a multiple-signal source, these signals can be transmitted in a serial multiplex mode or in coded form and are separated in the processor into the individual components.
Japanese patent application No. 62-95654 (A) entitled TRANSMISSION SYSTEM FOR ASYNCHRONOUS DATA to Jun Sato discloses an apparatus for reducing the number of control lines contained in a data transmission system. In the device data can be transferred with the handshake of rise and fall state changes caused by a single control line. This circuit arrangement, however, does not place the transmission and time sequencing in exclusive control of the processing means.
It is an object of the invention to provide a method and a circuit arrangement which make it possible to transmit the signals of a transmitter to a commercially available processor, particularly a microprocessor, the transmission and time sequence being controlled only by the processor.
It is another object of the invention to design the transmitter in such a way that the signal of the single-signal source or the signals of the multiple-signal source, which may be present in analog or digital form, are brought to a suitable digital form, so that a conventional single-pin input/output processor port (I/O port) can accept the signals, regardless of whether the input/output processor port has a push-pull output or an open output stage.
It is a further object of the invention to adapt the operation of the transmitter so that, as far as possible, any commercially available processor is capable of controlling the time sequence of the transmission by means of a suitable program statement as in a software program.